If you hanker for a quieter time, try Mae Nam on the north coast, a long stretch of golden sand that has the bonus of great sunsets.
For a more intimate experience, Thongtakian (Silver Beach) is a pretty little bay between Chaweng and Lamai that offers clear green water, powdery white sand and interesting reef and rock formations.
West coast beaches such as Lipa Noi offer a real get-away-from-it experience but be aware that many beaches, including parts of Lamai and Chaweng, can be affected by tides and wind, so do your research first.